SYNOPSIS

DESCRIPTION

interdiff creates a unified format diff that expresses the difference
between two diffs. The diffs must both be relative to the same files.
For best results, the diffs must have at least three lines of context.
To reverse a patch, use /dev/null for diff2.
To reduce the amount of context in a patch, use:
interdiff -U1 /dev/null patchfile
Since interdiff doesn’t have the advantage of being able to look at the
files that are to be modified, it has stricter requirements on the in-
put format than patch(1) does. The output of GNU diff will be okay,
even with extensions, but if you intend to use a hand-edited patch it
might be wise to clean up the offsets and counts using recountdiff(1)
first.
Note, however, that the two patches must both be relative to the ver-
sions of the same original set of files.
The diffs may be in context format. The output, however, will be in
unified format.

OPTIONS

-h Ignored, for compatibility with older versions of interdiff.
This option will go away soon.
-pn When comparing filenames, ignore the first n pathname components
from both patches. (This is similar to the -p option to GNU
patch(1).)
-q Quieter output. Don’t emit rationale lines at the beginning of
each patch.
-Un Attempt to display n lines of context (requires at least n lines
of context in both input files). (This is similar to the -U op-
tion to GNU diff(1).)
-dpattern
Don’t display any context on files that match the shell wildcard
pattern. This option can be given multiple times.
Note that the interpretation of the shell wildcard pattern does
not count slash characters or periods as special (in other
words, no flags are given to fnmatch). This is so that ‘‘*/base-
name’’-type patterns can be given without limiting the number of
pathname components.
-i Consider upper- and lower-case to be the same.
-w Ignore whitespace changes in patches.
-b Ignore changes in the amount of whitespace.
-B Ignore changes whose lines are all blank.
-z Decompress files with extensions .gz and .bz2.
--interpolate
Run as ‘‘interdiff’’. This is the default.
--combine
Run as ‘‘combinediff’’. See combinediff(1) for more information
about how the behaviour is altered in this mode.
--no-revert-omitted
(For interpolation mode only) When a file is changed by the
first patch but not by the second, don’t revert that change.
--help Display a short usage message.
--version
Display the version number of interdiff.

BUGS

There are currently no known bugs in interdiff; but there are some
caveats. If you find a bug, please report it (along with a minimal test
case) to Tim Waugh <twaugh@redhat.com>.
There are some sets of patches in which there is just not enough infor-
mation to produce a proper interdiff. In this case, the strategy em-
ployed is to revert the original patch and apply the new patch. This,
unfortunately, means that interdiffs are not guaranteed to be re-
versible.